The article below is excerpted from SERDP and ESTCP’s Partners in Environmental Technology Information Bulletin, Summer 2009 Issue. 

The Under Secretary of Defense for Acquisition, Technology and Logistics has issued a new policy for all DoD systems directed at reducing the usage of hexavalent chromium across the Department. The April 8, 2009 memo, Minimizing the Use of Hexavalent Chromium (Cr⁶⁺), calls out SERDP and ESTCP’s ASETSDefense initiative as the primary source of information on environmentally preferable alternatives that maintain performance and are costeffective. Hexavalent chromium, a known carcinogen, is used on most DoD weapons systems and platforms for its corrosion protection and other properties.

ASETSDefense—Advanced Surface Engineering Technologies for a Sustainable Defense—facilitates the implementation of new, environmentally friendly technologies for surface engineering (coatings and surface treatments) by providing ready access via a database to background information and technical data from research, development, test, and evaluation (RDT&E) efforts supported by DoD organizations and the private sector. ASETSDefense also provides access to information on the status of approvals and implementation of these alternative technologies. Defense organizations can apply this information and assistance to improve weapons system performance and life-cycle costs while reducing or eliminating environmental safety and occupational health (ESOH) impacts from coatings and treatment processes that use chemical compounds containing hexavalent chromium, coatings that contain cadmium, and coatings that contain volatile organic compounds (VOC).

Since their inception more than 14 years ago, SERDP and ESTCP have made substantial investments toward finding suitable replacements for Cr⁶⁺ for many DoD applications. An extensive amount of laboratory, component, and field testing has been conducted through numerous research, development, and demonstration projects. Examples of the resulting technologies now being implemented across DoD and the commercial sector include:

• The Hard Chrome Alternatives Team (HCAT), supported by ESTCP, validated high-velocity oxygen-fuel (HVOF) thermal spray coatings as a substitute for electroplated hard chrome, demonstrating improved performance and lower lifecycle costs. The HCAT program also showed the importance of assembling DoD-industry teams that would accelerate implementation of the alternative technology.
• Trivalent Chromium Pretreatment (TCP) has been developed to replace widely used chromate conversion coatings. (In this case, the oxidation state of the chromium is +3, with Cr³⁺ having significantly fewer environmental and worker safety issues than Cr⁶⁺.) The technology, developed by Naval Air Systems Command (NAVAIR) and demonstrated with ESTCP support, pretreats aluminum surfaces prior to coating. Now one of the most successful Cr⁶⁺-free treatments, TCP is available from several commercial vendors. It is finding applications beyond aluminum pretreatment, including sealing of coatings and possibly even pretreatment of steel and magnesium alloys.
• Programs to develop and validate powder coatings and ultravioletcurable paints, funded in part by SERDP and ESTCP, are leading to paint systems for vehicles and aircraft that not only eliminate Cr⁶⁺ but also cut down the drying time from days to hours. Aircraft and vehicles can be turned around and put back in service far faster and with a more protective, longer lasting coating.

In addition to ongoing efforts to develop Cr⁶⁺ alternatives, SERDP and ESTCP are funding projects that address other aspects of qualifying alternative coatings, such as developing accelerated corrosion and hydrogen embrittlement test methods that better simulate real-life conditions, environmentally friendly coating removal technologies, and methods for non-destructive inspection to detect corrosion beneath coatings.

For those charged with responding to the DoD policy memo, a central repository of information from these and other efforts is now available through the ASETSDefense Surface Engineering Database. This database is a relational database that provides access to documents and data required for making informed decisions on implementing clean coatings and surface treatments. It includes detailed engineering data, background documents, and information on processes and products that have been validated, authorized, or implemented. Database users can quickly identify which alternatives have been authorized, those that have been implemented, and the data underlying those decisions. The database contains information about alternatives to the following types of coatings: chromate conversion, chromate primers, hard chromium plating, chromic acid anodize, chromate metallic-ceramics, cadmium plating, chromate sealants, and high VOC materials.

Through periodic workshops, ASETSDefense facilitates information exchange leading to a more rapid qualification of alternative surface engineering technologies. These workshops bring together the entire supply chain and depot rework groups from all of the services to share experiences and data that will foster efforts to adopt alternative technologies and help determine the RDT&E still needed to improve technologies for DoD implementation. These workshops provide opportunities for individuals from government, industry, and academia to present key findings and results, encouraging open discussions among participants. ASETSDefense ’09: Sustainable Surface Engineering for Aerospace and Defense is planned for September 1-3, 2009, in Denver. This workshop will cover all ESOH coating issues in new and legacy aircraft, vehicles, and ships although special emphasis will be given to Cr⁶⁺ in response to the recent DoD policy memo.

For more information about ASETSDefense, please visit www.asetsdefense.org.